My Sis just picked up four bottles for me this morning. Was priced at £4.99 but when put through the till came up as £1.25 as per previous deal that was posted. When did the new price become effective?

I got 2 x 2.5litres of this stuff from Halfords today for £15 and 2 x Halfords screenwash for £5 had to get them to check screewash because it doesn't say BOGOF in store this is concentrated screenwash